Elsevier

Waste Management

Volume 29, Issue 10, October 2009, Pages 2625-2643
Waste Management

Recycling and recovery routes of plastic solid waste (PSW): A review

https://doi.org/10.1016/j.wasman.2009.06.004Get rights and content

Abstract

Plastic solid waste (PSW) presents challenges and opportunities to societies regardless of their sustainability awareness and technological advances. In this paper, recent progress in the recycling and recovery of PSW is reviewed. A special emphasis is paid on waste generated from polyolefinic sources, which makes up a great percentage of our daily single-life cycle plastic products. The four routes of PSW treatment are detailed and discussed covering primary (re-extrusion), secondary (mechanical), tertiary (chemical) and quaternary (energy recovery) schemes and technologies. Primary recycling, which involves the re-introduction of clean scrap of single polymer to the extrusion cycle in order to produce products of the similar material, is commonly applied in the processing line itself but rarely applied among recyclers, as recycling materials rarely possess the required quality. The various waste products, consisting of either end-of-life or production (scrap) waste, are the feedstock of secondary techniques, thereby generally reduced in size to a more desirable shape and form, such as pellets, flakes or powders, depending on the source, shape and usability. Tertiary treatment schemes have contributed greatly to the recycling status of PSW in recent years. Advanced thermo-chemical treatment methods cover a wide range of technologies and produce either fuels or petrochemical feedstock. Nowadays, non-catalytic thermal cracking (thermolysis) is receiving renewed attention, due to the fact of added value on a crude oil barrel and its very valuable yielded products. But a fact remains that advanced thermo-chemical recycling of PSW (namely polyolefins) still lacks the proper design and kinetic background to target certain desired products and/or chemicals. Energy recovery was found to be an attainable solution to PSW in general and municipal solid waste (MSW) in particular. The amount of energy produced in kilns and reactors applied in this route is sufficiently investigated up to the point of operation, but not in terms of integration with either petrochemical or converting plants. Although primary and secondary recycling schemes are well established and widely applied, it is concluded that many of the PSW tertiary and quaternary treatment schemes appear to be robust and worthy of additional investigation.

Abbreviations

ABS
acrylonitrile butadiene styrene
API
alliance for the polyurethane industry
ASR
automotive shredder residues
BFBs
bubbling fluidised beds
BHET
bis-(2-hydroxyethylene-terephthalate)
BTX
benzene, toluene and xylene
CAPE
carboxylated polyethylene
CCGT
combined cycle gas turbine
DEFRA
department of environment and rural affairs (UK)
DMSO
dimethylsulfoxide
DMT
dimethyltryptamine
ELTs
end-of-life tyres
FRs
flame-retardants
GCC
gulf council countries
GHGs
greenhouse gases
HCV
high calorific value
HDPE
high density polyethylene
IWM
integrated waste management
LCA
Life Cycle Assessment
LDPE
low density polyethylene
LHV
lower heating value
LLDPE
linear low density polyethylene
MAPE
maleated polyethylene
MDPE
medium density polyethylene
MSW
municipal solid waste
MSWI
municipal solid waste incinerator
MSWIPs
municipal solid waste incineration plants
PA 6
nylon 6 or polyamide 6
PAH
poly aromatic hydrocarbons
PBT
polybutylene theraphalate
PE
polyethylene
PEN
polyethylene (2,6-naphthalenedicarboxylate)
PET
polyethylene theraphalate
PI
polyisoprene
PMMA
polymethyl methacrylate
PP
polypropylene
PS
polystyrene
PSW
plastic solid waste
PU
polyurethane
PVC
polyvinylchloride
PVDF
polyvinylidene fluoride
R&D
research and development
RHDPE
recycled high density polyethylene
TBE
tetrabromoethane
TDM
titanium-derived mixture
VCC
viable cascade controller
XRF
X-ray fluorescent

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